Hate to contradict TT, but i have worn my fannypack on each coaster at least 5-7 times since the metal detectors were installed. Maybe they are giving me some leeway since i approach them w/ my insulin pump out and announce it, but i wear one all of the time.
Rides with lockers and no detectors don't even care, as i keep the pack under my shirt. You wouldn't know i had one if you happened to run into me at in a park. i often bring my wife's phone in that way so she can take pics on those rides.
Take that for what it's worth, but i definatley were a pack on the coasters.